Waveguide slot antenna with compact structure

Abstract

The invention relates to the technical field of antenna equipment, and particularly discloses a waveguide slot antenna with a compact structure, which comprises a substrate integrated cavity, an antenna radiation slot layer, a feed source excitation structure and an equivalent magnetic wall, the antenna slot layer is arranged on the lower surface of the substrate integrated cavity, the feed source excitation structure is arranged below the substrate integrated cavity, and the equivalent magnetic wall is arranged in the antenna radiation slot layer. And a distributed equivalent magnetic wall is formed on a medium-air interface passing through the side wall of the long edge of the waveguide. A TE20 mode is excited by adopting a microstrip line coupling slot feeding mode, and an equivalent magnetic wall is introduced in a matched manner, so that the surface current distribution of the substrate integrated waveguide is optimized, and the influence of radiation slot position offset caused by processing errors on the antenna performance is reduced. The introduction of the equivalent magnetic wall significantly reduces the size of the antenna, reduces the processing number of metal through holes, reduces the processing cost, and enables the antenna to be compact in structure and stable in performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna equipment, and in particular relates to a waveguide slot antenna with a compact structure. Background Art

[0002] Waveguide slot antenna is an antenna that uses waveguide to transmit electromagnetic waves and opens slots on the waveguide wall to radiate energy outward. Substrate integrated waveguide slot antenna has the advantages of easy manufacturing and integration, and is widely used in wireless communication systems and radar systems. When the antenna works at a higher frequency, the processing errors of the radiation slot position and size, the metal through-hole diameter and spacing in the manufacturing process will affect the performance of the antenna. One solution is to use the TE20 mode instead of the traditional main mode to reduce the number of metal through holes and simplify the structure of the antenna array. However, the feeding method of the antenna working in the TE20 mode is more complicated, and the size of a single antenna array element is twice the size of the antenna working in the main mode, which is not conducive to the miniaturization and integration of the antenna. The equivalent magnetic wall structure can simulate the magnetic wall characteristics at a specific location, change the propagation path and field distribution of the electromagnetic wave in the waveguide, and can reduce the size of the original waveguide and maintain or even improve the performance of the original waveguide. By introducing an equivalent magnetic wall structure into the substrate integrated waveguide and replacing the equivalent electric wall composed of metal through holes with the equivalent magnetic wall, the number of metal through holes in the substrate integrated waveguide can be reduced, and the processing cost and processing error of the metal through holes can be reduced. To this end, the present invention introduces an equivalent magnetic wall into the substrate integrated waveguide slot antenna, and proposes a compact waveguide slot antenna, so that the antenna is miniaturized while maintaining good performance. This antenna has the characteristics of compact structure, good stability, strong directivity, etc., and has a wide range of applications in radar, communication and other fields. Summary of the invention

[0003] The object of the present invention is to provide a waveguide slot antenna with a compact structure to solve the problems raised in the above background technology.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a compact waveguide slot antenna, comprising a substrate integrated cavity, an antenna radiation slot layer, a feed source excitation structure, and an equivalent magnetic wall. Among them, the antenna radiation slot layer is arranged on the lower surface of the substrate integrated waveguide to realize the radiation of electromagnetic energy; the feed source excitation structure is arranged below the substrate integrated cavity to excite the electromagnetic mode in the cavity through a specific feeding method; the equivalent magnetic wall is arranged on the side of the long side (along the wave conduction direction) of the substrate integrated cavity to limit the distribution of the electromagnetic field, thereby realizing the miniaturization and performance optimization of the waveguide structure.

[0005] Preferably, the main body of the substrate integrated cavity is a dielectric plate, the upper and lower parts of the dielectric plate are metal layers, and the metal through holes are located in the dielectric plate to connect the metal layers above and below the cavity, which together form a substrate integrated waveguide; based on the TE20 mode substrate integrated waveguide structure, an equivalent magnetic wall is placed along the long side of the waveguide at 1 / 4 and 3 / 4 of the short side of the waveguide, and only the field distribution within the range of 1 / 4 to 3 / 4 of the short side of the TE20 mode waveguide structure is retained, which can reduce the effective field distribution area by 50% and ensure that the radiation gap layer current is in phase within the wavelength range. The introduction of the equivalent magnetic wall reduces the cross-sectional area of ​​the waveguide by 50%, effectively reducing the size of the antenna and improving the space utilization.

[0006] Preferably, the present invention adopts a slot coupling feeding method, the excitation slot is set at the geometric center of the antenna radiation slot layer, and the electric field parallel to the narrow side of the slot is excited at the excitation slot by using a microstrip line coupling feeding method, thereby exciting the TE20 mode in the substrate integrated cavity. The waveguide slot antenna is centrally fed, and the electric fields on both sides are excited to be symmetrically distributed in the substrate integrated waveguide.

[0007] Preferably, the current distribution of the antenna radiation slot layer is characterized by: within each half wavelength range, the surface current is in phase. The antenna radiation slot is located in the same phase of the current of the antenna radiation slot layer, and the slot is symmetrically placed about the feeding port. The shape and size of the radiation slot are adjusted as needed to optimize the radiation performance.

[0008] Preferably, an equivalent magnetic wall is introduced into the long side wall of the substrate integrated waveguide, and the equivalent magnetic wall can be realized by a dielectric constant interface formed between the substrate medium and the air, or by other means of blocking the side wall current.

[0009] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. The present invention introduces an equivalent magnetic wall in the direction of the long side of the substrate integrated waveguide (in the direction of wave conduction) to replace the traditional metal through-hole array. Compared with the traditional substrate integrated waveguide slot antenna based on the main mode or TE20 mode, this solution effectively reduces the number of metal through-holes, helps to reduce production costs and improve manufacturing efficiency. At the same time, since the metal through-hole array is cancelled in the direction of wave propagation and only the metal through-hole array in the direction of the short side of the waveguide is retained, it helps to reduce the impact of the metal through-hole position deviation on the antenna performance during the manufacturing process, thereby improving the process controllability and stability of the antenna.

[0011] 2. The present invention utilizes the electromagnetic field distribution characteristics of the TE20 mode in the center of the waveguide to make the current on the waveguide surface distributed in phase within every 1 / 2 wavelength. Through this characteristic, the sensitivity of the radiation slot size and its specific position to the antenna performance is reduced, thereby simplifying the design requirements of the radiation slot. At the same time, the impact of the process deviation of the radiation slot on the antenna performance is also significantly reduced, further improving the production consistency and practicality of the antenna.

[0012] 3. By introducing an equivalent magnetic wall, the actual size of the short side of the waveguide is only half of the short side size of the traditional TE20 mode waveguide, which greatly reduces the overall cross-sectional area of ​​the waveguide. While the structure is compact, the manufacturing cost of the antenna is further reduced. In addition, the design combines efficient radiation performance with miniaturization advantages, is suitable for the application requirements of sparse antenna arrays, is easy to integrate into complex RF systems, and demonstrates good engineering practicality and scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of a compact waveguide slot antenna according to the present invention.

[0014] Figure 2 The figure is a schematic diagram of a compact waveguide slot antenna structure of the present invention.

[0015] Figure 3 Schematic diagram of the electric field distribution and surface current distribution of the substrate integrated waveguide cross section (side view), the upper part is the TE20 mode substrate integrated waveguide, and the lower part is the substrate integrated waveguide of the present invention.

[0016] Figure 4 This is the electric field intensity distribution diagram of the substrate integrated waveguide of the present invention.

[0017] Figure 5 It is the current vector diagram of the radiation slot layer in the substrate integrated waveguide of the present invention.

[0018] Figure 6 This is an S11 characteristic diagram of a compact waveguide slot antenna according to the present invention.

[0019] Figure 7 The beam pattern of a compact waveguide slot antenna at 10 GHz is shown in the figure.

[0020] Figure 8 This is a schematic diagram of a 1×2 antenna array composed of waveguide slot antennas of the present invention.

[0021] Fig. 9 This is the S11 characteristic diagram of the waveguide slot antenna of the present invention forming a 1×2 antenna array.

[0022] Fig.10The beam pattern of the 1×2 antenna array composed of the waveguide slot antenna of the present invention at 10 GHz. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1 and Figure 2 , the present invention provides a technical solution:

[0025] A compact waveguide slot antenna comprises the following stacked layers from top to bottom: a top metal layer 1, the material of which is set to be copper; a base integrated cavity 2, which is made of FR4 dielectric material with a dielectric constant of 4.4 and a loss tangent of 0.02; an antenna radiation slot layer 3, an excitation slot 4 is set at the geometric center of the antenna radiation slot layer, and the antenna radiation slot layer is made of copper; a microstrip line coupling excitation structure 5, which comprises an RF4 dielectric plate and a microstrip line transmission line with an input impedance of 50 ohms.

[0026] The top metal layer 1 of the substrate integrated cavity 2 is connected to the antenna radiation slot layer 3 through a periodically distributed metal through-hole array to form an electromagnetic shielding connection, forming a substrate integrated waveguide. The center frequency of the antenna in this embodiment is set to 10GHz, and the size of the substrate integrated waveguide structure is 14mm×32.4mm×0.785mm. The diameter of the metal through-hole is 0.6mm and the spacing is 1mm. The equivalent magnetic wall 6 is set on the long side of the substrate integrated cavity 2 to constrain the distribution of the electromagnetic field along the long side direction.

[0027] In one embodiment of the present invention, the optimized slot coupling feeding mechanism is as follows:

[0028] The excitation slot 4 adopts an "H"-shaped structure to realize electromagnetic coupling from the microstrip line to the substrate integrated waveguide, and is set at the geometric center of the antenna radiation slot layer 1. Its slot width is set to 1.47mm, and the height and width of the "H"-shaped structure are 4.16mm and 4.15mm respectively. The "H"-shaped excitation slot can reduce the coupling aperture and reduce the influence of the feeding microstrip line. Through the microstrip line coupling feeding method, the TE20 mode can be excited inside the substrate integrated cavity 2.

[0029] The equivalent magnetic wall miniaturization scheme adopted in this embodiment is as follows:

[0030] The equivalent magnetic wall 6 is realized by a dielectric interface with a significant dielectric constant difference formed between the substrate dielectric and the air.

[0031] According to electromagnetic field theory and waveguide theory, when the electric field in a waveguide is completely symmetrically distributed about the symmetry plane, this symmetry plane is an equivalent magnetic wall. If an equivalent magnetic wall is artificially set after cutting along this symmetry plane, the electromagnetic field type in the waveguide will remain consistent with the original electromagnetic field type. Figure 3 As shown, Figure 3 The above diagram shows the electric field and surface current distribution of the cross-section of the TE20 mode substrate integrated waveguide. The electric field in the waveguide is symmetrical in opposite strengths about the central axis of the waveguide, and the electric fields on the left and right sides of the central axis are completely symmetrical about the axis at the 1 / 4 and 3 / 4 positions in the short side direction (x direction), respectively. Figure 3 The following is a schematic diagram showing the electric field and surface current distribution of the cross-section of the substrate integrated waveguide proposed in the present invention. The substrate integrated waveguide proposed in the present invention is based on the TE20 mode waveguide structure, and an equivalent magnetic wall 6 is distributed along the long side direction (y direction) at the 1 / 4 and 3 / 4 positions in the short side direction, and only the field distribution within the range of 1 / 4 to 3 / 4 of the short side of the TE20 mode waveguide structure is retained, which can reduce the effective field distribution area by 50% and ensure that the radiation gap layer current is in phase within the 1 / 2 wavelength range. Figure 4 , Figure 5 The electric field intensity distribution diagram of the lower surface of the substrate integrated waveguide after the introduction of the equivalent magnetic wall and the current vector diagram of the radiation gap layer show that the electric field energy is concentrated near the magnetic wall, the current is in phase within the half-wavelength range, and the current is strongest near the center axis of the waveguide. The introduction of the equivalent magnetic wall reduces the cross-sectional area of ​​the waveguide by 50%, effectively reducing the size and weight of the antenna and improving space utilization.

[0032] The radiation gap setting scheme adopted in this embodiment is as follows:

[0033] A 2×2 rectangular longitudinal radiation slot 7 is provided in the antenna radiation slot layer 3 for radiation. The radiation slot 7 is located in the current phase in the antenna radiation slot layer 3, which can effectively reduce the sensitivity of the antenna performance to the size and specific position of the radiation slot, thereby simplifying the design and manufacturing. The slots are symmetrically distributed about the feeding port to ensure the symmetry of the electromagnetic radiation direction and the good radiation pattern characteristics of the antenna. The radiation slot length is 14.82mm, the width is 2.16mm, and the distance between the center of the radiation slot and the center axis of the waveguide is 4.9mm.

[0034] The position and size of the slot on the waveguide will introduce admittance into the waveguide equivalent circuit, affecting the coupling efficiency between the slot and the waveguide and the radiation efficiency of the antenna. A pair of metal through holes are symmetrically set on both sides of the "H"-shaped excitation slot for tuning to achieve better impedance matching. The diameter of the metal through hole is 0.6mm, and its center is 4.21mm away from the equivalent magnetic wall.

[0035] The key performance parameters of this embodiment are as follows:

[0036] The effective size of a single antenna unit is 14 mm × 32.4 mm × 1.57 mm (0.47λ × 1.08λ × 0.05λ), which has a small electrical size.

[0037] like Figure 6 As shown, Figure 6 The S11 characteristics of the antenna are demonstrated, and the -10dB impedance bandwidth is approximately 840MHz (9.44GHz-10.28GHz).

[0038] like Figure 7 As shown, Figure 7 The radiation pattern characteristics of the antenna at 10GHz are demonstrated, with a peak gain of 6.27dB and an E-plane -3dB beamwidth of 42°.

[0039] The array expansion implementation plan of this embodiment is as follows:

[0040] This antenna can be used as a basic radiation unit to construct an antenna array. Figure 8 The 1×2 antenna array composed of two of the above antennas was demonstrated, in which the microstrip feeding structure was designed as a half power divider structure, and a quarter impedance transformation section was used to achieve impedance matching between the 50 ohm microstrip line and the antenna. The distance between the two antenna array elements was 40.1 mm, and the overall size of the 1×2 antenna array was 14 mm×72.5 mm×1.57 mm (0.47λ×2.42λ×0.05λ).

[0041] like Fig. 9 As shown, Fig. 9 The S11 characteristics of the 1×2 antenna array are demonstrated, and the -10dB impedance bandwidth is approximately 1120MHz (9.68GHz-10.80GHz).

[0042] like Fig.10 As shown, Fig.10 The radiation pattern characteristics of the 1×2 antenna array at 10GHz were demonstrated. The array achieved a gain improvement of 9.25dB, the E-plane -3dB beamwidth was narrowed to 20°, and the sidelobe level was lower than -3.5dB.

[0043] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A compact waveguide slot antenna, characterized in that: It includes a substrate integrated cavity, an antenna radiation slot layer, a feed excitation structure, and an equivalent magnetic wall; wherein the antenna radiation slot layer is arranged on the lower surface of the substrate integrated waveguide, the feed excitation structure is arranged below the substrate integrated waveguide, and the equivalent magnetic wall is arranged on the long side of the substrate integrated cavity.

2. A compact waveguide slot antenna according to claim 1, characterized in that: The main body of the substrate integrated cavity is a dielectric plate, and the upper and lower parts of the dielectric plate are metal layers. Metal through holes are located in the dielectric plate to connect the metal layers above and below the cavity, forming a substrate integrated waveguide. Based on the TE20 mode substrate integrated waveguide structure, equivalent magnetic walls along the long side direction (y direction) are placed at 1 / 4 and 3 / 4 of the short side (x direction) of the waveguide, and only the field distribution within the range of 1 / 4 to 3 / 4 of the short side of the TE20 mode waveguide structure is retained, which can reduce the effective field distribution area by 50% and ensure that the radiation gap layer current is in phase within the wavelength range. The introduction of the equivalent magnetic wall reduces the cross-sectional area of ​​the waveguide by 50%, effectively reducing the size and weight of the antenna and improving space utilization.

3. The compact waveguide slot antenna according to claim 1, characterized in that: The feeding method is slot coupling feeding. The excitation slot is located at the center of the bottom metal layer of the substrate integrated waveguide. The microstrip line coupling feeding method is used to excite the electric field parallel to the narrow side direction of the slot (x direction) at the excitation slot, thereby exciting the TE20 mode in the substrate integrated cavity. The waveguide slot antenna is center-fed, and the electric fields on both sides of the substrate integrated waveguide are excited to be symmetrically distributed.

4. The compact waveguide slot antenna according to claim 1, characterized in that: The current distribution in the antenna radiation slot layer is as follows: within each half wavelength, the surface currents are in phase.

5. The compact waveguide slot antenna according to claim 1, characterized in that: The antenna radiation slot is located in the current phase of the antenna radiation slot layer, and the slot is symmetrically placed about the feeding port.

6. The compact waveguide slot antenna according to claim 1, characterized in that: The shape and size of the radiation gap are adjusted as required.

7. The compact waveguide slot antenna according to claim 1, characterized in that: An equivalent magnetic wall is introduced into the long side wall of the substrate integrated waveguide. The equivalent magnetic wall can be realized by a dielectric constant interface formed between the substrate medium and the air, or by other methods of blocking the side wall current.

Images